title: Effect of gender on the quadriceps-to-hamstrings coactivation ratio during different exercises.
abstract: BACKGROUND
  Coactivation ratio of quadriceps to hamstring muscles (Q:H) and medial to lateral knee muscles (M:L) contributes to the dynamic stability of the knee joint during movement patterns recommended during rehabilitation and important for daily function.
  
  
  OBJECTIVE
  To compare the quadriceps-to-hamstring and medial-to-lateral knee muscles' coactivation ratios between men and women during the following closed kinetic chain exercises performed on a balance board: forward lunge, side lunge, single-leg stance, and single-leg squat.
  
  
  METHODS
  Cross-sectional.
  
  
  METHODS
  20 healthy subjects (10 female and 10 male).
  
  
  METHODS
  Surface electromyography was used to measure the activation level of quadriceps (vastus lateralis and medialis) and hamstrings (biceps femoris and medial hamstrings) during forward- and side-lunge, single-leg-stance, and single-leg-squat exercises. Subjects were instructed during each exercise to move into the test position and to hold that position for 15 s. EMG was recorded during the 15-s isometric period where subjects tried to maintain a "set" position while the foot was on a balance board. Analysis of variance was used for statistical analysis.
  
  
  RESULTS
  There was a significant exercise-by-gender interaction for Q:H ratio (F3,48 = 6.63, P = .001), but the exercise-by-gender interaction for M:L ratio was not significant (F3,48 = 1.67, P = .18). Women showed larger Q:H ratio in side-lunge exercises than men (P = .002). Both genders showed larger M:L and lower Q:H ratio in a single-leg-stance exercise than in the other exercises.
  
  
  CONCLUSIONS
  The results indicate that the forward- and side-lunge and single-leg-squat exercises should not be recommended as exercise where a balanced coactivation between quadriceps and hamstring muscles is warranted. Single-leg-stance exercise could be used when seeking an exercise where the ratio is balanced for both women and men.
authors.affiliation: Dept of Physiotherapy and Rehabilitation, Hacettepe University, Ankara, Turkey.
authors.forename: Gulcan
authors.initials: G
authors.lastname: Harput
authors.forename: A Ruhi
authors.initials: AR
authors.lastname: Soylu
authors.forename: Hayri
authors.initials: H
authors.lastname: Ertan
authors.forename: Nevin
authors.initials: N
authors.lastname: Ergun
authors.forename: Carl G
authors.initials: CG
authors.lastname: Mattacola
mesh_terms: D000328:Adult; D003430:Cross-Sectional Studies; D004576:Electromyography; D005080:Exercise Test; D005260:Female; D006801:Humans; D007537:Isometric Contraction; D007717:Knee / Q000502:physiology*; D008297:Male; D009068:Movement / Q000502:physiology*; D052097:Quadriceps Muscle / Q000502:physiology*; D012737:Sex Factors; D055815:Young Adult